Electron transport chain is part of which of the following processes

The electron transport chain is the final and most important step of cellular respiration. While glycolysis and the citric acid cycle produce the necessary precursors, the electron transport chain is where the majority of ATP is created. 

It is a stepwise process of cellular respiration that is responsible for  producing:

1. water (with the help of the oxygen we breath)

2. up to 34 ATP molecules

3. NAD and FAD (which are recycled to be used again in the TCA cycle and glycolysis.)

The electron transport chain takes place in the mitochondria of eukaryotes and  cell membrane of prokaryotes.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

read more on -

the sphincter muscles at the end of the digestive tract is the anus.